what is tuple in f#
// Tuple of two integers.
( 4, 5 )
// Triple of strings.
( "one", "two", "three" )
// Tuple of unknown types.
( a, b )
// Tuple that has mixed types.
( "Absolute Classes", 1, 2.0 )
// Tuple of integer expressions.
( a * 4, b + 7)